pH in homemade skin care
When making skin and hair care products, it is important to be mindful of pH. It’s easy to forget this important step, as we tend to focus on the fun attributes like the look, smell and texture. While it is important for a product to look, smell and feel good it is much more important to ensure that the product has the correct pH for your skin. Without the right pH, your product in the best case scenario, won't work, and the worst case scenario will damage your skin.
What does pH mean?
The initials “pH” stand for “potential of hydrogen” as pH is the measure of hydrogen ion concentration in solution. The pH scale is logarithmic, so as a result, each whole pH step below 7 is ten times more acidic than the next higher value. So a pH 4 is ten times more acidic than pH 5 and 100 times more acidic than pH 6. So it’s clear that moving from a pH of 5 to a pH of 4 or 3 can have serious consequences. Pure water has a pH of 7 and is considered neutral. As you move away from pH 7 in either direction the ramifications of each step on the pH scale is great.
pH is also related to the functionality of a product. For example, the preservative potassium sorbate functions properly at a pH of 4.5. If you make a cream with this preservative, all the ingredients in the cream also need to be able to work at that ph, and not all ingredients do. So if you have a list of ingredients you want to use, you must be sure they can all work together at the same pH.
Skin has a protective layer on its surface called the acid mantle. The acid mantle is made up of sebum excreted from the skin’s sebaceous glands. The sebum mixes with lactic and amino acids from sweat creating the skin’s pH, which ideally should be somewhere between 4.5 -5.5. All skincare products should be tested to ensure they remain within this range. A good practice is to test pH directly after making the product, and again in 30 days to make sure the pH hasn’t changed. pH can be affected by a variety of reasons including ingredients, preservatives, temperatures, and time.
pH and Color
pH can have a huge effect on color, especially when using natural colorants such as the biocolour we use. This color can be from dark blue to completely clear depending on the pH. It’s best to test your colorants in different pH solutions to determine if the pH of your product will let you have the color you want. Although for DIY products, I would never worry about using a natural colorant because they can be tricky if you are not a cosmetic chemist.
How to Test pH
Testing pH is very easy. Just dip the strip into the product and match the color on the strip to the color on the scale.
The easiest way to lower pH is to use Citric Acid. If you need to increase pH, Baking Soda is also an easy to use solution. Neither of these will hurt your skin. Simply add in small amounts until the formula reaches the target pH making sure each of the ingredients work at the target pH.
What can you do with this information? While we can’t go into depth to teach you all the chemistry behind it, it is helpful to keep a set of pH strips on hand for your DIY projects, especially for face products. You can also test the pH of products you buy to make sure they are correctly formulated.
I hope you found this helpful.